): Patterns of terrestrial ecological imprints and feedbacks and their implications on climate change adaptation in the wooded savannah of Nigeria.
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Date
2012
Authors
Fasona, M.J
Journal Title
Journal ISSN
Volume Title
Publisher
START International Inc, Washington D.C.
Abstract
Background
Significant climate change expected over the 21st century will affect ecosystems, natural resource systems and rural livelihoods especially in dry and semi-dry environments where large population depends on natural resource stock. Restored and well managed, but climate-sensitive natural resource systems can become human shock absorbers, targets for climate change mitigation, and fulcrum for adaptation strategies. Climate and landcover interaction is a two way feedback. Understanding the implication of this feedback for climate change adaptation requires detailed and local knowledge. A degree of localised eco-geographical factors create eco-climatic complex which often vary by season and area and controls the local climate in the wooded savannah of Nigeria. This study demonstrates that integrated remote sensing and GIS models have the potential to compliment regional climate models to analyze climate-landcover relations and feedback at high spatial resolution.
Methodology
The eco-geographic variables were integrated within a GIS and statistically analysed using principal component analysis (PCA). The result was profiled for association and feedbacks between climate and the variables and to also determine the principal controlling factors of the local climate in both present and future scenario. Classified landcover image maps derived from Landsat data for 1986, 2000 and 2006 formed the base landcover data. Change drivers developed by integration of Markov probabilities matrix, transition areas and conditional probability for landcover classes with suitability maps for landcover categories computed from rainfall, maximum temperature and local eco-geographic factors were also used to simulate future landcover from 2006 to 2046 under present and future climate scenarios using Idrisi’s dynamic CA_Markov model.
Results
The results suggest a local climate system driven mainly by the coupling between terrain (with associated vegetal cover), rainfall and temperature in all seasons. Under present climate, this eco-climatic complex predominates around the southeast-northwest corridor in all seasons except June-July-August (JJA). The system spatially reverses to the southeast-northeast corridor in JJA, which also coincides with the period of the West African monsoon. The southeast-northeast corridor especially across the Niger receives maximum rainfall. This pattern is projected to continue in future scenario. However, the spatial influence of the climate-orographic complex will diminish around the northwest, while the system will weaken with rainfall becoming less significant in the system in JJA. The pattern of rural settlements and rural landuse suggests that livelihood systems of the local population are directly connected to this local eco-climatic complex. This complex is also the single source of all major drainage of the entire western Nigeria. Recovery from the droughts of the 1970s and 1980s was suggested by increased canopy ecosystems and significant decrease in shrub/grassland, bare surface and fire scar. Under present climate scenario urban lands is projected to progressively increase by about 270% from 577km2 in 2006 to 2136km2 representing 5.4% of total landcover in 2046. A corresponding increase in area under cultivation is also projected with a peak of about 12% of total landcover in 2016 (from 8% in 2006) and stabilizes around 10% from 2026 to 2046. The largest growth of settlements and cultivated lands is projected for the areas around the northwest-southeast corridor especially the headwaters of Ogun river (Oke-ogun) areas. Although total forest area is expected to decline by about 378km2 between 2006 and 2046, its overall coverage as percent of total landcover is projected to increase to 18% in 2016 and stabilizes around 15% from 2025 to 2046. The strongest transition gain of 110% over 2006 coverage is expected from shrub and grassland. Projection based on future climate suggests significant decline in the coverage of the two canopy ecosystems – forest and woodland- from 2016 to 2046. Galleria forest - a signature of the upper Guinea and Sudan savannah - is projected to dominate presently forested landscapes. Shrub and grassland will be much more widespread. A shift in rural settlement and agrarian landuse is also expected with more settlements and cultivated lands emerging around the middle areas especially at fringe of the protected area. Aggressive vegetation and albedo enhancement and ecotourism are tipped as viable climate change mitigation options. Adaptation strategies will benefit from existing project platforms that address local natural resource systems, rural livelihoods, resource conflicts, and community driven development.
Description
Scholarly article
Keywords
Climate , landcover change , Mitigation , Savannah , Nigeria , Factor maps , Research Subject Categories::SOCIAL SCIENCES
Citation
The African Climate Change Fellowship Program: Round 1 Final Reports, 2008-2010, Vol 2, p611-628, START International Inc, Washington D.C. Also available at: http://start.org/download/accfp/fasona-final.pdf, International START Secretariat, Washington DC, USA